The invention relates to a system for performing an analysis of a cell sample containing cell objects and particularly to such a system which enables operators of the system to influence the portion of the cell sample to be analyzed.
One of the problems which faces pathologists in their clinical practice is that of determining whether a cell sample taken from a patient during a biopsy procedure or the like is benign or malignant. Although a surgeon may have a good intuition about the type of tissue mass which he has removed, nevertheless he must confirm his preliminary diagnosis with a histological examination of the cell sample removed from the patient. The histological examination entails cell staining procedures which allow the morphological features of the cells to be seen relatively easily in a light microscope. A pathologist after having examined the stained cell sample, makes a qualitative determination of the state of the tissue or the patient from whom the sample was removed and reaches a conclusion as to whether the patient is normal or has a premalignant condition which might place him at risk of a malignancy in the future or has cancer. While this diagnostic method has provided some degree of predictability in the past, it is somewhat lacking in scientific rigor, since it is heavily reliant on the subjective judgment of the pathologist.
Systems have been designed which automate the cellular examination process. In U.S. Pat. No. 4,741,043 to Bacus for Method and Apparatus for Image Analyses of Biological Specimens, an automated method and a system for measuring the DNA of cell nuclei are disclosed which employ differential staining of the DNA in cell nuclei and image processing. Cell objects which comprise cell nuclei are automatically selected, the DNA mass of each nucleus is then measured and a histogram is generated to show the frequency of nuclei having particular DNA masses.
The system of the above-mentioned Bacus patent, digitizes an optical image of a cell sample and selects for analysis cell objects of interest by identifying continuous perimeters around the cell objects. For most cell objects in cell samples, this yields satisfactory results, however, in some instances, cell objects can be difficult for the apparatus to distinguish. For example, when two cell objects are abutting one another, they present an optical image which appears continuous and which has a single perimeter surrounding both objects. Such abutting cell objects may be interpreted by automated apparatus as a single cell object, resulting in slightly inaccurate results, particularly when a measured quantity is reported on a per cell object basis. Also the cell objects may be arranged in such a way that it is not possible for the apparatus to select certain desirable cell objects for analysis. This might occur when the gray scale values of the background and the cell objects and the background are similar and overlapping.
Automated methods of identifying the boundaries of objects in images are also described in "Digital Image Processing", Second Ed., 1987 by R. C. Gonzalez and P. Wintz and "Video Microscopy", 1986 by Shinya Inoue'.
In order to select and appropriately analyze cell objects of the difficult to distinguish type, a need exists for an apparatus which permits human operators to modify the apparent boundaries of cell objects in the cell sample image, and to thereby influence the selection of cell objects for analysis.